One of the most amazing things about human beings is that no matter where you travel in the world, you will find evidence of man's amazing commitment to religion. The great pyramids of Giza, the cathedrals of Britain, the great statue of Christ in Peru or the stone carvings on Easter Island. The time, effort and resources that have been invested over thousands of years in creating these structures is simply mind-boggling.

Whether it is a belief in God, Christ, Buddha, Mohamed, or that we are the reincarnated souls of beings from another planet, more than 85% of the world's population profess to hold some form of religious belief. In the last census in the UK almost three quarters of the population described themselves as being Christian.

Some would argue that the mere prevalence of religion amongst the world's population is proof that there must be a God, while others would argue that religions are simply a means by which rationalise the unknown and deal with the fear of death. In this article I am not aiming to support or oppose either view, but simply to look at the neurological underpinnings of faith.

To understand man's infatuation with religion we need to begin by looking back to the earliest signs of religious belief - to a time when humans were just evolving from our primate ancestors around 2.5 million years ago.

It is now well known that the two halves of the human brain perform different functions. It is also known that at some stage in our evolution this was not the case. Why the human brain developed this specialisation is not known for certain but it is interesting to note that the development of this specialisation appears to coincide with the development of art and religion.

So why did the two halves of the brain develop differently? Theories laid out by Corballis in his book The Lopsided Ape suggest that lateralisation of the brain occurred because of the development of language, which itself originated from the development of gesture. His theory is that as the climate of the African continent changed, the forests turned to grassland and food became more dispersed. This favoured our ancestor Homo Habilis (handy man) who had begun making tools and had a relatively large brain. Casts of brains from that period suggest the first development of the Broca area which is used for language, although the throat and mouth were not yet sufficiently developed for speech.

Since Homo Habilis was walking upright, he would have had both hands free to gesture. He would also have been free to develop specialisation in use of his limbs, i.e. become right- or left-handed. This, Corballis suggests, was when the functions of the hemispheres started to become specialised. He believes that the brain power needed to develop language was so great that the brain did not have sufficient capacity to develop it evenly within each hemisphere. The symmetry of the brain was therefore lost as language developed as a primarily left hemisphere function and spatial awareness became a function primarily of the right hemisphere.

The language of gesture would therefore have developed as a set of left-brained rules and conventions. These would have subsequently been broadened in their meaning by vocal sounds, facial expressions and body language that originate in the right side of the brain. As spoken language developed the same applied; the left hemisphere being responsible for the syntax while the right hemisphere is responsible for the emotion of language.

In his book The Soul in the Brain, Michael Trimble suggests that the advent of religious belief is associated with this separation of the functions of the hemispheres. With the two hemispheres free to develop in their own particular way, language blossomed from the left and poetry, music, art and religion emerged from the right.

This association between art and religion has been noted by many other commentators. For example, Otto Rank, who was a colleague and friend of Freud, pointed out that in the evolution of the human mind, the development of art and religion closely parallel each other. Viewed from the perspective of religion the associations are also plain to see with the obvious examples being psalms, hymns and religious art and sculpture. Indeed, in ancient Greece, poets were actually regarded as gods.

Trimble's conclusion is that religious belief emerged as man's way of interpreting the "voices" of the right hemisphere. Take the opening lines of the famous poem Auguries of Innocence by William Blake as an example:

To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour.

These are just words, yet they are capable of evoking an emotional response in many people. Other examples could be the "I have a dream" speech by Martin Luther King or the "We will never surrender" speech by Churchill.

Although not everyone is a great poet, musician or artist, we all have a right side to our brains and are therefore affected to some extent by right-sided stimulus. While the language of the left hemisphere is logical, structured and with a purpose; the thoughts, ideas and concepts of the right hemisphere may at times appear to be spontaneous or even illogical. It is therefore easy to see why we might interpret the language of the left as being internally inspired (the "voice of man") and the language of the right being externally inspired (the "voice of God").

It is interesting that neuroscience is developing to the point where we are able to gain an understanding of something as complex as religious belief. It is also interesting that despite our vast scientific knowledge, we are still no nearer to proving the existence of God or otherwise. Obviously some people will interpret these findings as proof that there is no God, others will point out that if there is no God, why do we have a form of "antenna" in the right hemisphere that appears to be attuned for external stimulation?

It's nice to know that some things will never be resolved.

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